In the dental field, it is often necessary to make a cast of a patient's teeth, a dental model, upon which dental hardware may be fabricated to fit a patient's teeth. Such a model may be made by first taking a negative impression of a patient's teeth and gums and then filling the model with a suitable casting material. After the casting material hardens, dowel pins are rigidly mounted in the dental model and a base cast is formed over the dental model. When the base cast is hardened, portions of the dental model may be separated by vertical cuts through the dental model. This enables selected portions of the dental model to be removed from the base cast so that they can be easily worked on. When the removable model portions are replaced, it is necessary to rotationally align the dental model portions with respect to the base cast so that the dental model will be stable and correspond accurately to the configuration of the patient's teeth.
Several types of dowel pins have been utilized to removably mount and rotationally align a dental model on a base cast. One such mounting device includes two parts. The first part has two differently sized dowel pins extending therefrom, and is mountable in a dental model with the dowel pins extending outwardly. The second part is mountable in a base cast and carries two appropriately sized openings for receiving the dowel pins.
Another prior art device similarly comprises a first metal part having two dowel pins, the dowel pins being receivable in a channel of a second metal part carried by a base cast. One of the dowel pins of the device is significantly shorter than the other. A similar device includes two separate dowel pins of different diameters carried by the dental model, the pins extending from the model to be received within two separate sleeves carried by a base cast.
Another prior art device comprises a single metal piece carried by a dental model having two dowel pins extending outwardly from the dental model to be received directly within two holes carried by the stone of a base cast.
Yet another prior art device includes two separate pins. One metal pin is carried by the dental model and received within an opening carried by the stone of a base cast. The other pin is made of plastic and is carried by the base cast extending outwardly, generally parallel to the pin carried by the model, the pin being receivable in an opening carried by, the dental model.
The dowel pins appearing in the prior art are generally, expensive to manufacture and often unduly complicated or cumbersome, preventing close spacing of the pins, such as for closely spaced teeth. In use, some tend to loosen in their engagement with their mating part, resulting in a loose fit between the dental model and the base cast.